Viewing contents of file '../idllib/astron/pro/date_conv.pro'
function date_conv,date,type
;+
; NAME:
; DATE_CONV
; PURPOSE:
; Procedure to perform conversion of dates to one of three possible formats.
;
; EXPLANATION:
; The following date formats are allowed
;
; format 1: real*8 scalar encoded as:
; year*1000 + day + hour/24. + min/24./60 + sec/24./60/60
; where day is the day of year (1 to 366)
; format 2: Vector encoded as:
; date(0) = year (eg. 1987)
; date(1) = day of year (1 to 366)
; date(2) = hour
; date(3) = minute
; date(4) = second
; format 3: string (ascii text) encoded as
; DD-MON-YEAR HH:MM:SS.SS
; (eg. 14-JUL-1987 15:25:44.23)
; OR
; YYYY-MM-DD HH:MM:SS.SS (ISO standard)
; (eg. 1987-07-14 15:25:44.23)
; format 4: three element vector giving spacecraft time words
; from a Hubble Space Telescope (HST) telemetry packet.
;
; CALLING SEQUENCE
; results = DATE_CONV( DATE, TYPE )
;
; INPUTS:
; DATE - input date in one of the three possible formats.
; TYPE - type of output format desired. If not supplied then
; format 3 (real*8 scalar) is used.
; valid values:
; 'REAL' - format 1
; 'VECTOR' - format 2
; 'STRING' - format 3
; TYPE can be abbreviated to the single character strings 'R',
; 'V', and 'S'.
; Nobody wants to convert TO spacecraft time (I hope!)
; OUTPUTS:
; The converted date is returned as the function value.
;
; NOTES:
; Prior to Oct 1998, the returned real*8 date (format 1) was given as
; (year-1900)*1000 + day + hour/24. + min/24./60 + sec/24./60/60
; This output is ambiguous with respect to the year 2000. Note that the
; current version of DATE_CONV() may not be backwards compatible with
; versions prior to Oct 1998.
;
; HISTORY:
; version 1 D. Lindler July, 1987
; adapted for IDL version 2 J. Isensee May, 1990
; Made year 2000 compliant; allow ISO format input jls/acc Oct 1998
; DJL/ACC Jan 1998, Modified to work with dates such as 6-JAN-1996 where
; day of month has only one digit.
;-
;-------------------------------------------------------------
;
; data declaration
;
days = [0,31,28,31,30,31,30,31,31,30,31,30,31]
months = [' ','JAN','FEB','MAR','APR','MAY','JUN','JUL','AUG','SEP','OCT',$
'NOV','DEC']
;
; set default type if not supplied
;
if n_params(0) lt 2 then type = 'REAL'
;
; Determine type of input supplied
;
s = size(date) & ndim = s[0] & datatype = s[ndim+1]
if ndim gt 0 then begin ;vector?
if ndim gt 1 then goto,notvalid
if (s[1] ne 5) and (s[1] ne 3) then goto,notvalid
if (s[1] eq 5) then form = 2 else form = 4
end else begin ;scalar input
if datatype eq 0 then goto,notvalid
if datatype eq 7 then form = 3 $ ;string
else form = 1 ;numeric scalar
end
;
; -----------------------------------
;
;*** convert input to year,day,hour,minute,second
;
; -----------------------------------
case form of
1: begin ;real scalar
idate = long(date)
year = long(idate/1000)
;
; if year is only 2 digits, assume 1900
;
if year lt 100 then begin
print,'DATE_CONV: Warning: Year specified is only 2 digits, assuming 19xx'
year=1900+year
idate=1900000+idate
date=1900000.+date
end
;
day = idate - year*1000
fdate = date-idate
fdate = fdate*24.
hour = fix(fdate)
fdate = (fdate-hour)*60.0
minute = fix(fdate)
sec = float((fdate-minute)*60.0)
end
2: begin ;vector
year = fix(date[0])
if year lt 100 then begin
print,'DATE_CONV: Warning: Year specified is only 2 digits, assuming 19xx'
year=1900+year
end
;
; if year is only 2 digits, assume 1900
;
if year lt 100 then begin
print,'DATE_CONV: Warning: Year specified is only 2 digits, assuming 19xx'
year=1900+year
end
;
day = fix(date[1])
hour = fix(date[2])
minute = fix(date[3])
sec = float(date[4])
end
3: begin ;string
temp = date
;
; check for old type of date, DD-MMM-YYYY
;
if strpos(temp,'-') le 2 then begin
day_of_month = fix(gettok(temp,'-'))
month_name = gettok(temp,'-')
year = fix(gettok(temp,' '))
hour = fix(gettok(temp,':'))
minute = fix(gettok(temp,':'))
sec = float(strtrim(strmid(temp,0,5)))
;
; determine month number from month name
;
month_name = strupcase(month_name)
for mon = 1,12 do begin
if month_name eq months[mon] then goto,found
end
print,'DATE_CONV -- invalid month name specified'
retall
;
; check for new type of date, ISO: YYYY-MM-DD
;
end else if strpos(temp,'-') eq 4 then begin
year = fix(gettok(temp,'-'))
month_name = gettok(temp,'-')
mon=month_name
day_of_month=gettok(temp,' ')
if strlen(temp) eq 0 then begin
dtmp=gettok(day_of_month,'T')
temp=day_of_month
day_of_month=dtmp
end
day_of_month=fix(day_of_month)
hour = fix(gettok(temp,':'))
minute = fix(gettok(temp,':'))
sec = float(strtrim(strmid(temp,0,5)))
end else goto, notvalid
found:
;
; if year is only 2 digits, assume 1900
;
if year lt 100 then begin
print,'DATE_CONV: Warning: Year specified is only 2 digits, assuming 19xx'
year=1900+year
end
;
;
; convert to day of year from month/day_of_month
;
; correction for leap years
;
; if (fix(year) mod 4) eq 0 then days(2) = 29 ;add one to february
lpyr = ((year mod 4) eq 0) and ((year mod 100) ne 0) $
or ((year mod 400) eq 0)
if lpyr eq 1 then days[2] = 29 ; if leap year, add day to Feb.
;
;
; compute day of year
;
day = fix(total(days[0:mon-1])+day_of_month)
end
4 : begin ;spacecraft time
SC = DOUBLE(date)
SC = SC + (SC LT 0.0)*65536. ;Get rid of neg. numbers
;
; Determine total number of secs since midnight, JAN. 1, 1979
;
SECS = SC[2]/64 + SC[1]*1024 + SC[0]*1024*65536.
SECS = SECS/8192.0D0 ;Convert from spacecraft units
;
; Determine number of years
;
MINS = SECS/60.
HOURS = MINS/60.
TOTDAYS = HOURS/24.
YEARS = TOTDAYS/365.
YEARS = FIX(YEARS)
;
; Compute number of leap years past
;
LEAPYEARS = (YEARS+2)/4
;
; Compute day of year
;
DAY = FIX(TOTDAYS-YEARS*365.-LEAPYEARS)
;
; Correct for case of being right at end of leapyear
;
IF DAY LT 0 THEN BEGIN
DAY = DAY+366
LEAPYEARS = LEAPYEARS-1
YEARS = YEARS-1
END
;
; COMPUTE HOUR OF DAY
;
TOTDAYS = YEARS*365.+DAY+LEAPYEARS
HOUR = FIX(HOURS - 24*TOTDAYS)
TOTHOURS = TOTDAYS*24+HOUR
;
; COMPUTE MINUTE
;
MINUTE = FIX(MINS-TOTHOURS*60)
TOTMIN = TOTHOURS*60+MINUTE
;
; COMPUTE SEC
;
SEC = SECS-TOTMIN*60
;
; COMPUTE ACTUAL YEAR
;
YEAR = YEARS+79
;
; if year is only 2 digits, assume 1900
;
if year lt 100 then begin
print,'DATE_CONV: Warning: Year specified is only 2 digits, assuming 19xx'
year=1900+year
end
;
;
; START DAY AT ONE AND NOT ZERO
;
DAY=DAY+1
END
ENDCASE
; ---------------------------------------
;
; ***** Now convert to output format
;
; ---------------------------------------
;
; is type a string
;
s = size(type)
if (s[0] ne 0) or (s[1] ne 7) then begin
print,'DATE_CONV- Output type specification must be a string'
retall
end
;
case strmid(strupcase(type),0,1) of
'V' : begin ;vector output
out = fltarr(5)
out[0] = year
out[1] = day
out[2] = hour
out[3] = minute
out[4] = sec
end
'R' : begin ;floating point scalar
; if year gt 1900 then year = year-1900
out = sec/24.0d0/60./60. + minute/24.0d0/60. + hour/24.0d0 $
+ day + year*1000d0
end
'S' : begin ;string output
;
; correction for leap years
;
if form ne 3 then begin ;Was it already done?
; if (fix(year) mod 4) eq 0 then days(2) = 29
lpyr = ((year mod 4) eq 0) and ((year mod 100) ne 0) $
or ((year mod 400) eq 0)
if lpyr eq 1 then days[2] = 29 ; if leap year, add day to Feb.
end
;
; check for valid day
;
if (day lt 1) or (day gt total(days)) then begin
print,'DATE1-- There are only',total(days),' in year ',year
retall
end
;
; find month which day occurs
;
day_of_month = day
month_num = 1
while day_of_month gt days[month_num] do begin
day_of_month = day_of_month - days[month_num]
month_num = month_num+1
end
month_name = months[month_num]
;
; encode into ascii_date
;
; if year lt 1900 then year = year+1900
out = string(day_of_month,'(i2)') +'-'+ month_name +'-' + $
string(year,'(i4)') + ' '+ $
string(hour,'(i2)') +':'+ $
strmid(string(minute+100,'(i3)'),1,2) + ':'+ $
strmid(string(sec+100,'(f6.2)'),1,5)
end
else: begin ;invalid type specified
print,'DATE_CONV-- Invalid output type specified'
print,' It must be ''REAL'', ''STRING'', or ''VECTOR'''
retall
end
endcase
return,out
;
; invalid input date error section
;
notvalid:
print,'DATE_CONV -- invalid input date specified'
retall
end